Electrical outlet plug



\ l l E E. G. SCHAEFFER 2,312,496

ELECTRICAL OUTLET PLUG Filed April 9, 1941 fan 4R0 & 56l/AEFFER A TTOR/VEYS Patented Mar. 2', 1943 UNITED STATES PATENT orrlclz' ELECTRICAL OUTLET PLUG Edward G. Schaefl'er, Holyoke, Mass. Application April 9, 1941, Serial No. 384,603

3 Claims. (Cl. 173361) This invention has to do with electric outlet plugs of the type which include a body of insulation material and a pair of contact prongs of conducting material to which the terminals of theconductor wires are connected and the invention is directed to an improved construction of plug and method of producing the same.

The invention primarily comprehends an improved method of producing an outlet plug of the character set forth by means of which the assembly of the contact prongs with the plug body is facilitated and a secure and lasting connection therebetween is insured as long as'the body remains intact.

The invention further resides in certain improvements in the structure of the contact prongs which render the connection between the same and the plug body more effective, together with improved means provided on the prongs for establlshing connection of the conductor wires therewith.

The invention is further directed to an electric outlet plug consisting of a body of insulation material having an axially extending opening formed with an oblong mouth portion provided with oppositely arranged recesses spaced from the end of the mouth portion and a pair of contact prongs having lateral anchoring projections which are positioned at the opposite ends of the mouth portion and are provided with lateral anchoring projections disposed within the recesses and which are secured in place by a block of insulation material frictionally fitted within the mouth portion of the opening between the contact prongs.

With the above recited and other obj cts in view, the invention is set forth in greater detail in the following specification and illustrated in the accompanying drawing in which:

Fig. 1 is a longitudinal sectional view illustrating an electric outlet plug body being molded with the mold sections shown in associated relation during the molding operation.

Fig. 2 is a collective view showing the molded plug body removed from the mold with the mold sections in separated juxtaposition thereto.

Fig. 3 is a sectional view on the line 33 of Fig. 1.

Fig. 4 is a collective sectional view taken on the line 4-4 of Fig. 2.

Fig. 5 is a longitudinal sectional view of the finished outlet plug with the wiring attached to the contact prongs.

Fig. 6 is a longitudinal sectional view taken approximately on the line 6-6 of Fig. 5.

Fig. I is an end view of a plug.

Fig. 8 is a detail perspective view of one of the contact prongs.

Referring to the drawing by characters of reference, the plug body 40 which is composed of hardened plastic material, such as hard rubber, is provided with a recess 4| of cross sectional oblong shape extending axially inward from the forward end 42 of the plug body and providing parallel opposite side walls 43 respectively formed intermediate the ends with oppositely disposed grooves or depressions 44 in spaced adjacent relation to the forward end 42 of the plug body.

The recess 4| is also defined by parallel opposite end wall portions 45 extending inwardly from the forward end of the plug body terminating in the region of the grooves or depressions 44 and merging into forwardly diverging end wall portions 46 to provide at the juncture with the end wall portions 45 undercut clearance spaces 41. The plug body 40 is formed with an axially extending opening 48 extending inwardly from the rear end 49 thereof and communicating with the recess 4| to provide a bore for receiving therethrough the extension cord 50 housing the conductor wires 5|.

The outlet plug further includes a pair of contact prongs 52 each of which is preferably cut, bent and formed from a flat strip of metal bent upon itself intermediate the ends to provide a double ply outer end portion 53 for engagement within an electric outlet socket. The single ply inner end portion 54 of each contact prong which is adapted to be arranged within the recess 4| of the plug body, is provided intermediate its ends with lateral projections 55 spaced from the double ply portion an appropriate distance to register with the grooves or depressions 44 when the contact prongs are assembled with the plug body. The inner end portions 54 are each provided further with a reversely bent terminal 56 defining a bendable terminal clip for clamping engagement with the conductor wires 5| for attaching the same thereto.

In assembling the contact prongs with the plug body, the inner end portions are inserted in the recess 4| with the projections 55 extending lengthwise of the recess or parallel to the side walls 43 until the projections 55 align with the grooves or depressions 44. The prongs are then turned in a direction so that the reversely directed terminals 56 are disposed towards the end Walls 45 with the projections 55 engaging in the opp sitely disposed grooves or depressions 44 and the inner end portions 54 are brought into fiat contact with the end wall portions 45 while the terminal clips with the conductor wires 5| sejecting outwardly therefrom.

portion. A block I! ofinsulation material of a width to snugly fit and frictionally engage the side walls 43 and of a length to clamp the prongs in fiat contact respectively with the opposite end wall portions 48 is then forcibly wedged into the recess with its outer end surface flush with the forward end 4'! of the plug body. This effectually secures the prongs in assembled relation with the plug body with the outer end portions I! pro- This also spaces the uninsulated terminals of the conductor wires II and provides effective insulation between the contact prongs throughout the entire length of the inner end portions I4. In event that it is desired .to detach the plug from the conductor wires, an instrument may be inserted through the opening or bore a to force the block I! outwardly and thereby permit of the disassembly of the contact prongs from the plug body.

In producing an electric outlet plug of the type illustrated,-the following method is employed: A two part mold is used including a mold body A having a mold cavity B which conforms to the exterior configuration of the plug 40. A mold cap C is adapted to be arranged over the open side of the mold and is provided with a core D of the recess having depressions extending longitudinally of said side walls to the end walls thereof and spaced from the mouth of the recess, a pair of contact prongs each having a pair of lateral projections adjacent the inner end thereof to provide an inner end portion of greater width than the width of the mouth of said recess, said prongs having theirinner end portions disposed in said recess in engagement with the opposite end walls thereof respectively with the projections extending into said depressions, and a block of insulation material fitted within the recess between said pair of prongs and functioning to clamp the prongs in fiat contact respectively with the opposite end walls of the recess.

2. In an electric outlet plug, a body of insulation material-having a recess of cross sectional oblong shape extending axially inward adapted to be emplaced in the mold cavity B to form the recess 4| and opening or bore 48. The

core D is provided with ofiset depression or groove forming portions E at opposite sides thereof and oppositely projecting portions 1" for forming the undercut clearance spaces. The method consists in initially molding the plug body ll in the mold cavity B and about the core D as illustrated in Figs. 1 and 3 of the drawing, the molding operation being carried out so as to leave the insulation material of which the body is formed in a yieldable resilient state. The mold body A and the mold cap 0 are then separated and the molded plug body while in the yieldable resilient state, is stripped from the core D, it being understood that the yieldable resilient state permits of the flexing or yielding of the body to permit the projecting portions E and F to be separated. The plug body is then treated to harden the same, such as by heating, to produce vulcanization thereof. The contact prongs 52 are then inserted in the recess ll in the manner previously specified and the insulation block I! is frictionally fitted into the recess between said pair of prongs for securing the inner end portions of the I prongs within the, plug body with the outer end portions protruding therethrough.

What is claimed is: y

1. In an electric outlet plug, a body of insulation material having a recess of cross sectional oblong shape extending axially inward from the forward end of the plug body, opposite side walls from the forward end of the plug body, opposite side walls of the recess having depressions extending longitudinally of said side walls to the end walls thereof and spaced from the mouth of the recess, a pair of contact prongs each having a pair of lateral projections adjacent the inner end thereof to, provide an inner end portion of greater width thanthe width of the mouth of said recess, said prongs having their inner end portions disposed in said recess in engagement with the opposite end walls thereof respectively with the projections extending into said depressions, bendable terminal clips formed integral with the inner extremities of the contact prongs for clamping conductor wires thereto, said recess having an outwardly fiared portion at each end thereof providing undercut clearance spaces for accommodating the terminal clips and permitting the prongs to fiatly contact with the end walls of the recess adjacent the forward end of the plug body, and a block of insulation material fitted within the recess between said pair of prongs and functioning to clamp the prongs in fiat contactrespectively walls of the recess.

' each having a pair of lateral projections adjacent the inner end thereof to provide an inner end portion of greater width than'the width of the mouth of said recess, said prongs having their inner end portions disposed in said recess in engagement with opposite walls thereof respectively and with the projections extending into said depressions, and a block of insulation material fitted within the recess between said pair of prongs and functioning to clamp the prongs against said opposite walls of the recess.

EDWARD G. SCHAEFFER.

with the opposite end 

